Put the chocolate in a small, heat-safe bowl. In a small saucepan, over low heat, simmer the whipping cream, peppermint leaves, zest, and agave nectar for 2 minutes. Pour the infused hot cream through a sieve into the bowl of chocolate. Discard mint leaves. Whisk chocolate and cream until smooth and glossy. Cool to room temperature. Cover and refrigerate overnight. When ready to assemble, use a small ice cream scoop or teaspoon and portion out about a tsp. of the hardened mixture. Roll between the palms of your hands until you have a small ball. Roll in unsweetened cocoa powder or powdered sugar to coat. Keep refrigerated. Recipe by Andi Phillips, excerpted from The Functional Foodie: 50 Powerhouse Ingredients Go Gourmet.